Last Thursday when I went to work and walked over to my corner of the workshop I saw a big silver amp sitting on a cart next to my neighbor's workbench and about messed my pants. There sat a somewhat abused A-1020!
I kinda freaked out and started babbling, "Where did this come from? Whose is it? What's going to happen with it?". Etc. So about then in walks my co-worker with a handfull of cheap caps from our benchstock. Turns out that the amp belongs to an aquantance of ours that wants to get it repaired. It has "bad sound", and a number of bulging caps in it, is plated with nicotine, and has any number od scratches and dents. 3 caps look like the have been replaced at some time in the past as they are a bright orange (2) and green (1). It made me really sad and a bit bewildered to see that this fine amp had been so obviously abused.
So I stopped my pal from attacking it with those caps until I could find out more about what the owner wanted and if he realized what he really had, and what he really wanted to have done. Then I called the owner and got an ok to look into finding 1) quality replacement caps, 2) a new protection relay, 3) quality replacement idle current pots.
So far I've found owners and service manuals from HiFi Engine, and done a google search of the forums here and found the following...
http://www.audiokarma.org/forums/showthread.php?t=450408
So now I have a cap replacement list thanks to 4seatPilot and I can start to look for those locally.
http://www.audiokarma.org/forums/showthread.php?t=279810
I'm pretty sure that we have a 24v Finder relay with gold contacts in our benchstock that will work, if not I will be able to find what is needed locally.
http://www.audiokarma.org/forums/showthread.php?t=379693
http://www.audiokarma.org/forums/showthread.php?t=455327
I don't think that I'll need output transistors (supposedly it supplies sound in both channels but with crosstalk and noise) but if so am hoping that those linked above are still valid and available.
I have Deoxit on hand as well as other localally produced cleaning agents. And we have a dim bulb tester in the shop. I'm only a passable hand at soldering but my foreman is a wonder and will be going over all of the solder points.
I remember reading on a different Yamaha thread that the fusable resistors in these amps can drift over time. Valid? Shouls I replace them? If so can someone point me to which type and brand etc that I should be looking for? A quick look on Friday showed that there are about 30 of them scattered through the amp. I'll have to make a list next week.
Thanks to Karl vd Berg I have links to and info about the trim pots.
http://www.audiokarma.org/forums/showthread.php?t=631520
I'll take some pics tomorrow and post them.
Is there anything else that I'm overlooking that I shouldn't be? It'd be nice to hear this thing sing again, even if I won't be able to take it home.
Cheers,
James
edit 24-Feb-2019: I have updated my parts list and am moving it here, as that seems to be a lot more logical than having it on post#31.
A note about the list. As a non MS or Apple user I don't have any of their Office products and use LibreOffice. I realize that this can be a pita for some people who don't want to have to download and install an extra program just to view this list.
So I also exported it to a pdf form and both that and the spreadsheet are included in the zipfile. Alas the pdf is translated to 3 pages that will have to be taped together to be usable. I'm sorry about that but it's the best that I could do at this time.
Also, you will notice that many of the parts choices in the list are now (February 2019) different than what is discussed in the following thread. This reflects what I have learned since 2015 and different choices that I make now. As with any such list treat it as a starting point and not Gospel.
I kinda freaked out and started babbling, "Where did this come from? Whose is it? What's going to happen with it?". Etc. So about then in walks my co-worker with a handfull of cheap caps from our benchstock. Turns out that the amp belongs to an aquantance of ours that wants to get it repaired. It has "bad sound", and a number of bulging caps in it, is plated with nicotine, and has any number od scratches and dents. 3 caps look like the have been replaced at some time in the past as they are a bright orange (2) and green (1). It made me really sad and a bit bewildered to see that this fine amp had been so obviously abused.
So I stopped my pal from attacking it with those caps until I could find out more about what the owner wanted and if he realized what he really had, and what he really wanted to have done. Then I called the owner and got an ok to look into finding 1) quality replacement caps, 2) a new protection relay, 3) quality replacement idle current pots.
So far I've found owners and service manuals from HiFi Engine, and done a google search of the forums here and found the following...
http://www.audiokarma.org/forums/showthread.php?t=450408
So now I have a cap replacement list thanks to 4seatPilot and I can start to look for those locally.
http://www.audiokarma.org/forums/showthread.php?t=279810
I'm pretty sure that we have a 24v Finder relay with gold contacts in our benchstock that will work, if not I will be able to find what is needed locally.
http://www.audiokarma.org/forums/showthread.php?t=379693
http://www.audiokarma.org/forums/showthread.php?t=455327
I don't think that I'll need output transistors (supposedly it supplies sound in both channels but with crosstalk and noise) but if so am hoping that those linked above are still valid and available.
I have Deoxit on hand as well as other localally produced cleaning agents. And we have a dim bulb tester in the shop. I'm only a passable hand at soldering but my foreman is a wonder and will be going over all of the solder points.
I remember reading on a different Yamaha thread that the fusable resistors in these amps can drift over time. Valid? Shouls I replace them? If so can someone point me to which type and brand etc that I should be looking for? A quick look on Friday showed that there are about 30 of them scattered through the amp. I'll have to make a list next week.
Thanks to Karl vd Berg I have links to and info about the trim pots.
http://www.audiokarma.org/forums/showthread.php?t=631520
I'll take some pics tomorrow and post them.
Is there anything else that I'm overlooking that I shouldn't be? It'd be nice to hear this thing sing again, even if I won't be able to take it home.
Cheers,
James
edit 24-Feb-2019: I have updated my parts list and am moving it here, as that seems to be a lot more logical than having it on post#31.
A note about the list. As a non MS or Apple user I don't have any of their Office products and use LibreOffice. I realize that this can be a pita for some people who don't want to have to download and install an extra program just to view this list.
So I also exported it to a pdf form and both that and the spreadsheet are included in the zipfile. Alas the pdf is translated to 3 pages that will have to be taped together to be usable. I'm sorry about that but it's the best that I could do at this time.
Also, you will notice that many of the parts choices in the list are now (February 2019) different than what is discussed in the following thread. This reflects what I have learned since 2015 and different choices that I make now. As with any such list treat it as a starting point and not Gospel.
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